1. Field of the Invention
This invention relates to brake master cylinders for vehicles and more particularly to an inlet union of tandem brake master cylinder in which dual brake fluid pressures are applied independently of each other to sets of wheel brake cylinders.
2. Description of the Prior Art
Conventionally, various tandem brake master cylinders have been proposed which include two inlet unions which are, in turn, connected by means of hoses to a tandem reservoir secured to a vehicle body. The two inlet unions are attached to a cylinder body of the master cylinder and may be molded of resinous material such as nylon in order to reduce weight and cost. Each inlet union has a tubular portion which is inserted within an inner wall of a boss provided on the cylinder body, a further tubular portion which is inserted within one end of the hose, and a mounting flange which has two insertion holes for mounting screws so as to face the top of the boss. Thus, each inlet union is mounted on the cylinder body by means of the mounting screws which are threaded therethrough. In a case where the mounting flange is tightened too much by means of the mounting screws, there is the possibility that the mounting flange will be cracked. In order to avoid this possibility of cracking, the diameter of the mounting screw has been set so as to be less than that of the insertion hole and the length of large diameter shaft portion of the mounting screw has been set so as to be greater than the thickness of the mounting flange. Moreover, such play in the inlet unions may be relatively large due to the clearances between the insertion hole and the mounting screw and between the mounting flange and the top of the boss of cylinder body. Therefore, the sealing function of the sealing members which are positioned between the inlet unions and the bosses of the cylinder body may be damaged, especially since the inlet unions are caused to be moved in assembly of a vehicle and in maintenance of and repair work on the vehicle. Moreover, inlet unions may develop play due to vibration during vehicle running.